Teach gecko profile processing to use the marker schema to properly offset timestamps

[gregtatum]

Right now we have lots of custom handling. This could be done purely with marker schema.

e.g. for Network markers:

      if (newData.type === 'Network') {
        if (typeof newData.domainLookupStart === 'number') {
          newData.domainLookupStart += delta;
        }
        if (typeof newData.domainLookupEnd === 'number') {
          newData.domainLookupEnd += delta;
        }
        if (typeof newData.connectStart === 'number') {
          newData.connectStart += delta;
        }

┆Issue is synchronized with this Jira Task